KYIV, Ukraine (AP) — A desperately needed delivery of aid and the evacuation of civilians from the besieged Ukrainian city of Mariupol remain in doubt following reports of continued Russian interference. Russian officials accused Ukraine of flying helicopter gunships across a border between the two countries and striking an oil depot early Friday. The governor of Russia’s Belgorod region said the alleged airstrike caused multiple fires and two people were injured. A Kremlin spokesman said the incident on Russia’s territory could undermine negotiations between Russian and Ukrainian negotiators that resumed by video link. Claims that Ukrainian helicopters targeted the oil depot and also struck several nearby businesses in Belgorod couldn’t be independently verified.